1. Field of Invention
The present invention relates to a compensation device for non-uniform regions in a flat panel display and a method thereof. More particularly, the present invention relates to a compensation device for non-uniform regions in a flat panel display through digital signal processing and a method thereof.
2. Description of Related Art
Various flat panel displays are developed directing to eliminate the disadvantages of conventional CRT displays, such as heaviness and bulkiness. The flat panel displays can be classified into CRT displays, liquid crystal displays (LCDs), plasma displays, organic light emitting diode (OLED) displays and so on. Each of the above flat panel displays has its own advantages.
For an LCD, the fabricating process of the LCD panel relates to complicated combination and materials such as plates of backlight module, polarizing films, brightness enhancement films, press fit of two glass substrates. If a slight fault happens in one fabrication step of the LCD, observable non-uniform regions will appear when a final light-on test is performed, wherein the fault is the so-called mura phenomenon such as bad pixel or non-uniform gray-scale or color. Moreover, observable non-uniform regions of various degrees may also appear after the light-on test as the light provided by the plates of backlight module is not uniform.
Therefore, the non-uniform regions are generally a phenomenon of poor display caused by, for example, non-uniformity in the plates of backlight module and fabrication processes of the display. The characteristics of the non-uniform regions or mura are, for example, distorted gray scales/colors with uncertain shapes. First, for the distorted gray scales/colors, the common non-uniform regions include, for example, white spots, dark spots, bright regions and dark regions, wherein the white spot and the dark spot represent that some pixel has defects, and the dark region and the bright region represent that the pixels in the region have defects. Next, the appearance of the non-uniform regions can be, for example, lateral stripes, 45° stripes, or straightly cut blocks appearing in one corner or scattering everywhere irregularly.
The non-uniform regions that greatly impact the visual feeling generally attribute to the faults during the fabricating or assembling processes. In order to reduce the non-uniform regions, the manufacturers usually improve the processes to eliminate the mura phenomenon, for example, improving materials, thickness, etching, physical property/chemical property recipes, fabrication processes, etc. in de-mura, mura-free fields. Additionally, as an LCD panel is formed by a combination of two glass substrates, the faults occurred in the combination of the glass substrates may also lead to non-uniform regions. Moreover, in another aspect, the faults in the designing, manufacturing and assembling of the backlight module plate of the LCD may also result in the non-uniform regions.
Therefore, directing to the causes of the non-uniform regions, the occurrence thereof can be reduced by improving the fabrication processes. Moreover, the causes of the non-uniform regions can be detected/classified by setting up several automatic monitoring stations during the processes for improvement. However, the aforementioned improving manner also has disadvantages. For example, the improvement of processes has to change the process parameters, such that the fabrication processes of a panel become more complicated. Additionally, the set-up of the monitoring stations also results in a significant increase in the manufacturing cost of the panel. U.S. Patent Publication No. 20040179028 discloses a process compensation method, which increases the cost in the fabrication process or panel design. Moreover, U.S. Patent Publication No. 20050007364 discloses a process inspection method, which significantly increases the complexity of the fabrication process.
Accordingly, in the de-mura or mura-free fields, a technology for processing non-uniform regions in a panel through signal processing must be provided. Through the technology, the fabrication processes are not changed, and the non-uniform regions in the panels are processed appropriately.